Jonsson Tech BB250-2 | 250A 58VDC Busbar — 2 × M8 Posts, 150 mm² Nickel-Plated Copper, V-0 Cover

The Jonsson Tech BB250-2 is a two-post DC busbar for 12 V, 24 V and 48 V systems — 150 mm² of nickel-plated copper on 40 mm centres, rated 250 A continuous to 58 V DC, with a flame-retardant cover that goes on last and comes off first.

It was designed around one rule: no plastic in the bolted joint. On most moulded busbars the stud clamps down through the plastic body, and plastic under a torqued joint creeps. The joint relaxes, resistance climbs, and the bar runs hot — which is the one failure mode a busbar must not have. Here the clamp load runs bolt head → steel sleeve → copper → lug → washer → nut. Every element in that path is metal, and the plastic carries none of it.

Built for the current, not just rated for it

• 150 mm² conductor — 70 × 25 × 6 mm nickel-plated copper, 5 µm minimum plating. At 250 A that's 1.67 A/mm², and under 0.3 W of loss across the 40 mm between posts.
• 25 mm wide bar — a 2/0 lug tongue is supported across its full width. No overhang, no point loading at the crimp.
• Two M8 stainless posts on 40 mm centres, torqued to 13 N·m (115 in-lb), with 22.4 mm of stud above the bar — enough thread to land two lug tongues on one post, with 4.6 mm to spare.
• Steel-sleeved posts. The sleeve, not the plastic, takes the clamp. Torque it once and it stays torqued.

A cover that works the way you install

• Its own two screws, outboard of the base. Mount the base, land your cables, then drop the cover on. You never have to back out a mounting screw after the cables are connected — and the cover comes off later without disturbing the base or the lugs.
• Scalloped cable guides. An arch over each post, sized to clear a 2/0 crimp barrel, so the cover drops straight down over cables that are already landed. Cables exit left, right, or both.
• Flame-retardant throughout. Base and cover are both printed in UL 94 V-0 rated flame-retardant polycarbonate (PC-FR) — not just the base.
• Countersunk mounting screws sit flush in the ears and feet. Nothing stands proud of either surface.
• Strain relief pads built into the base, 0.2 mm under each lug tongue, so a cable pulled sideways loads the base and not the crimp.

Printed and assembled in Spring, Texas. Made to order by a Victron-trained installer who builds these systems for a living.

Specifications

In the box

• 1 × busbar base with nickel-plated copper bar fitted
• 1 × flame-retardant cover
• 2 × M8 × 35 stainless post bolts, with steel load sleeves, flat washers and nuts (fitted)
• 2 × M5 flat-head base mounting screws
• 2 × M4 flat-head cover mounting screws

Good to know

• Not finger-safe to IP2X — the cable arches are open by design so the cover fits over landed cables. Mount it in a locker or enclosure, as you would any open busbar.
• 58 V DC is the rating for lithium and lead systems up to 48 V nominal. DC only.